This invention relates to bayonet-type heaters containing gas burners of long length and relatively small transverse section. More particularly, the heaters of this invention have a tubular heat exchange shell encasing a tubular porous fiber burner attached to a long feed tube for the fuel gas-air mixture.
Electric bayonet-type heaters have long enjoyed diverse applications such as domestic water heaters, commercial food cookers, and air or gas heaters. Because of the compactness of electric bayonet-type heaters, it has not been possible heretofore to use gas burners in lieu of the electric resistance elements commonly employed in bayonet-type heaters. Of course, there is a substantial economic advantage in generating heat with fuel gas rather than with electricity. In many places. the cost of heat from electricity is at least two to three times the cost of heat from fuel gas such as natural gas. Hence, there has long been a need for a gas burner capable of being substituted for electric resistance elements in bayonet-type heaters.
A principal object of this invention is to provide a simple gas burner which can be inserted in the casing of a bayonet-type heater and operated to deliver heat efficiently through the casing to the medium in contact therewith.
Another important object is to provide a tubular porous fiber burner of small diameter attached to a long gas-air feed tube so that the gaseous products of combustion will flow through the annular space between the burner and the bayonet-type casing counter to the flow of the fuel gas-air stream fed to the burner.
These and other objects and advantages of the invention will be evident from the description which follows.